Is lanthanum a metal?

Yes. Lanthanum is a metal, classified as a lanthanide on the periodic table.

How many protons does lanthanum have?

Lanthanum has 57 protons. Its atomic number is 57, which is also the number of electrons in a neutral atom of lanthanum.

What group and period is lanthanum in?

Lanthanum is in period 6 of the periodic table. As a lanthanide in the f-block, it sits in a separate row below the main table and has no standard group number.

What is the atomic mass of lanthanum?

The atomic mass of lanthanum is 138.91 u (unified atomic mass units).

Element 57

Lanthanum (La)

Lanthanide · Period 6 · f-block

Lanthanum (La) is element 57 of the periodic table, a lanthanide in period 6 (f-block) with an atomic mass of 138.91 and is a solid at standard conditions.

At a glance

Atomic number: 57
Symbol: La
Atomic mass: 138.91 u
Category: Lanthanides
Period: 6
Block: f-block
Phase at STP: solid

Electron structure

Electron configuration: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 5d1 6s2
Shorthand configuration: [Xe] 5d1 6s2
Electrons per shell: 2, 8, 18, 18, 9, 2
Oxidation states: +1, +2, +3

Physical properties

Melting point: 1,193 K (919.85 °C)
Boiling point: 3,737 K (3,463.85 °C)
Density: 6.145 g/cm³
Phase: solid

Atomic properties

Electronegativity (Pauling): 1.1
Atomic radius: 195 pm
Covalent radius: 207 pm
First ionization energy: 538 kJ/mol
Electron affinity: 50 kJ/mol

Notable isotopes

Notable isotopes of Lanthanum: mass number, atomic mass, natural abundance, and stability.
Isotope	Mass	Abundance	Stability
La-139	138.90635	99.91%	Stable

Common uses

Hybrid car batteries
Camera lenses
Lighting
Catalysts

Discovery

Year: 1839
Discovered by: Carl Gustaf Mosander
Country: Sweden

Frequently asked questions

Is lanthanum a metal?: Yes. Lanthanum is a metal, classified as a lanthanide on the periodic table.
How many protons does lanthanum have?: Lanthanum has 57 protons. Its atomic number is 57, which is also the number of electrons in a neutral atom of lanthanum.
What group and period is lanthanum in?: Lanthanum is in period 6 of the periodic table. As a lanthanide in the f-block, it sits in a separate row below the main table and has no standard group number.
What is the atomic mass of lanthanum?: The atomic mass of lanthanum is 138.91 u (unified atomic mass units).

Keep exploring

Lanthanum's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.